The invention relates to optical instruments and in particular housings for optical instruments; and optical components adapted to be accommodated by said housings.
Light, isotropic or otherwise, refracted by lenses and/or reflected by mirrors is used in any number of optical devices. The conventional selection and arrangement of lenses and mirrors can be used to advantage to make, amongst other things, optical instruments that magnify images. Examples of such optical instruments include microscopes and telescopes. Both of the aforementioned instruments magnify images, but the latter is specifically adapted to view distant objects. The way light is manipulated in any number of optical instruments will not be considered herein in great detail, suffice to say that it is well known to those skilled in the art that a selected combination of lenses and mirrors can be used to advantage to alter the path of light for any selected purpose, including, but not limited to, the ones aforedescribed.
Common to all optical instruments is the need to provide at least one optical path, that is to say optical components must be precisely positioned with respect to each other in order to ensure that light entering the instrument travels a predefined pathway. Thus, for example, light may be made to focus at a given location before, for example, being made to travel in an alternative direction or even being split to provide for a multiplicity of beams which are similarly made to travel in a predetermined direction, where each resultant beam may be made to travel in a different direction with respect to the other resultant beams.
It will be apparent from the above that the alignment and positioning of optical components in an optical instrument is critical and/or crucial. This can be illustrated having regard to the optical schematic shown in FIG. 1.
The microscope represented in FIG. 1 comprises a fibre optic light source 1xc3x97 which, briefly, emits a beam of light that is focused by refraction, via lens 2xc3x97 and compensated via a compensating plate 3xc3x97. The beam of light is then used to illuminate an object and is reflected from same so as to strike a beamsplitter plate 4xc3x97 and to be reflected through an angle of 90xc2x0 and thus made to travel along an axis perpendicular to the optical axis and towards two cameras 5xc3x97 and 6xc3x97 (one with a narrow field of view and one with a wide field of view). Although in the microscope illustrated in FIG. 1 light is directed towards cameras it may be alternatively directed towards an eyepiece. In the arrangement shown, the lenses are selected so as to provide a magnified image of the object to be viewed.
The positioning of each optical component in the aforedescribed optical system is critical if a distortion-free image is to be achieved. For example, if lens 1 and the beamsplitter plate are misaligned then a distorted image will be obtained which will appear ultimately on the camera as an inaccurate representation of the image to be viewed.
Hitherto, the manufacture of optical instruments has involved machining a housing with a plurality of bores, each bore being machined to accommodate selected optical components. It will apparent that as the machining takes place the orientation of the housing will be sequentially changed and that the machining process will take place in intervals. This process of periodic machining, in combination with a change in housing orientation, introduces errors into the alignment of housing bores and thus into the alignment of optical components positioned within the housing. Moreover, the bores are machined so as to frictionally hold each of said components. However, it will be apparent that any machining of this type must involve a certain amount of tolerance if the optical component is in fact to pass through the bore. Thus it is possible for any optical component so positioned to be misaligned by only a small amount but by an amount sufficient to deleteriously affect the image to be achieved.
It follows from the above that the greater the number of optical components to be positioned within a housing then the greater the propensity for error and the more difficult the task. This is especially true for microscopes because they use a combination of lenses in order to provide for enhanced magnification since magnification is determined by the product of the separate magnification of each lens.
In addition to the above, the positioning and alignment of square-shaped components is rendered difficult using a conventional housing because of the differences in geometry.
It therefore follows that hitherto the manufacture of optical instruments has involved a considerable amount of time, skill and labour. Moreover the manufacturing tolerance of such instruments is in the order of tens of microns eg 20-30 microns for the type of microscope illustrated in FIG. 1.
In addition to the above, and in particular in relation to microscopes, it has always been the case that the turret for accommodating objective lenses has been mounted on the microscope so that its angle from the vertical is offset, for example, by 19xc2x0. The offset angle is designed to prevent impact between an objective lens and an object which may result because of the different working lengths of various objective lenses. The mounting of the turret at an angle is a feature that involves a considerable amount of engineering since a part of the instrument to which the turret is to be attached has also to be similarly machined so that it can accommodate a turret mounted at an angle to the vertical. Similarly, other fixtures and fittings are affected by this safety feature and thus represent a manufacturing investment in terms of labour, skill and time.
Given the above information, it is an object of the invention to provide a housing for an optical instrument which enables the assembly of the instrument in an inexpensive and a relatively easy fashion.
It is a further object of the invention to provide a housing that can be machined in a way that involves a relatively small number of machining steps and ideally a single setting for a machining tool.
It is yet a further object of the invention to provide a housing which enables an optical instrument to be assembled with relatively little skill.
It is yet a further object of the invention to provide a housing which facilitates the alignment of optical components to a common optical axis and moreover provides for the reliable and reproducible alignment of said components. It is therefore an object of the invention to provide a housing which facilitates the creation of an optical pathway.
It is another object of the invention to provide a housing which enables the registration of optical components.
It is yet a further object of the invention to provide a housing which minimises aberrations in an optical image and thus provides for a more desirable optical instrument.
It is yet a further object of the invention to provide a housing which reduces the time required for assembly and alignment of the system, which exhibits mechanical and thermal stability, which reduces the hitherto complexity of the optical instrument system and so eases manufacture and reduces the emphasis on manufacturing tolerance and which also provides for simple and easy repair and replacement of any one or more component(s) of the optical system.
It is also a further object of the invention to provide optical components adapted to fit in the housing of the invention so as to be securely and reliably held in place and so as to be easily replaceable especially for repair and maintenance.
In its broadest aspect, the invention concerns a groove or channel having at least two surfaces positioned perpendicular with respect to each other so as to provide reference surfaces against which a component can be positioned.
According to a first aspect of the invention there is therefore provided a housing for an optical instrument which housing is provided with at least one channel means having, in section, at least two sides thereof positioned at right angles with respect to each other so as to provide two reference surfaces against which optical components can be positioned.
In a preferred embodiment of the invention said channel means is provided on an inner side of said instrument and more preferably comprises a square or rectangular slot such that the bottom and one upstanding side provide said reference surfaces.
It will be understood that the channel means will be adapted to accommodate the optical components to be referenced therewith. For example, the width of the channel will be such that the largest optical component of the system will fit therein; and further the depth of the channel will be such that the largest optical component of the system will make contact with both the base of the channel and a sufficient amount of the upstanding side of the channel so as to securely locate the optical component in position. For example, in one preferred embodiment of the invention the depth of the channel will be slightly greater than the radius of any given component.
In yet a further preferred embodiment of the invention a plurality of channel means are provided within a given housing, and more preferably still, at least two of said channel means will be arranged to intersect so as to provide for a T-junction or X-junction.
It will apparent from the above that the provision of a housing including a number of locating reference channels easily and quickly enables a number of optical components to be positioned within the housing in register so as to ensure the integrity of the optical path. Moreover, it also follows, that removal and replacement of a given optical component can be undertaken in the secure knowledge that the position of alignment will not change and thus the integrity of the optical path will not be compromised. Indeed, the manufacturing tolerance of an instrument in accordance with the invention is in the order of less than 10 microns ie at least an order of magnitude greater than prior art instruments.
In yet an alternative embodiment of the invention optical components are fixedly retained within the housing by magnetic means. For example, in one embodiment of the invention a magnet is provided in said channel means. Preferably, a recess is provided within at least one of said reference surfaces which recess is sized and shaped to accommodate a magnet and ideally the magnet is flush with, or more preferably underflush with the said surface(s). Thus, ideally clearance is provided between the magnet and the optical component so as to maintain the semi-kinematic properties of the system, however it will be appreciated, that the retaining forces are maximised by minimising the distance between the component and the magnet. Where a cylindrical optical component is to be positioned a magnet may be provided in a cavity defined by a corner of the reference sides and the lower curvature of the optical component. In this embodiment, ideally the magnet is provided with an outer or working surface whose curvature matches that of the optical component or which is at least at an angle of 45xc2x0.
In an alternative embodiment of the invention mechanical means may be provided to hold each optical component in place, for example, biased screw and/or bolt means may be provided which are adapted to exert a retaining force on the optical component having a maximum upper limit such that the optical component cannot be damaged or deformed when securely held in position.
It will be apparent from the above that the invention provides for reliable and reproducible alignment of optical components. It also, advantageously, provides for the mounting of a turret without the need to provide an offset angle. In other words a turret can be mounted flat on the housing so overcoming the need to invest in expensive and time consuming machining of the housing and turret.
According to a further aspect of the invention there is provided a housing for an optical instrument which is adapted to have flatly mounted thereon a turret for accommodating objective lenses.
In a preferred embodiment of the invention said housing is provided with a flat surface that is either parallel or perpendicular with at least one channel means in accordance with the invention so that said turret is aligned with the optical axis of the housing.
In this preferred embodiment of the invention, means, ideally automatic, is provided for moving the turret and/or objective lens with respect to the object to be viewed so as to safeguard against damage to said object.
It will be apparent that the housing of the invention has a number of applications in the provision of optical instruments and although it has been, and will be, described in this document with particular reference to a microscope it is not intended that the protection should be limited thereby. Rather, it will apparent to all those skilled in the art that the housing of the invention has multiple applications in the provision of any number and nature of optical instruments where the need to provide an optical axis or pathway is crucial to the working of the instrument.
An embodiment of the invention will now be described by way of example only with reference to the following figures wherein;